U.S. patent application number 17/429247 was filed with the patent office on 2022-05-05 for electrode device.
The applicant listed for this patent is NATIONAL UNIVERSITY CORPORATION KUMAMOTO UNIVERSITY, NITTO DENKO CORPORATION. Invention is credited to Kyosei GOTO, Tatsuya KITAHARA, Masashi KUNITAKE, Mitsunobu TAKEMOTO.
Application Number | 20220136992 17/429247 |
Document ID | / |
Family ID | 1000006128325 |
Filed Date | 2022-05-05 |
United States Patent
Application |
20220136992 |
Kind Code |
A1 |
KUNITAKE; Masashi ; et
al. |
May 5, 2022 |
ELECTRODE DEVICE
Abstract
An electrode device includes a first electrode, a second
electrode, and an ion-conducting medium extending over and in
contact with the first electrode and the second electrode. The
ion-conducting medium is made of a bicontinuous microemulsion
including a water phase as a continuous phase and an oil phase as a
continuous phase. At least one of the water phase and the oil phase
is a gel.
Inventors: |
KUNITAKE; Masashi;
(Kumamoto-shi,Kumamoto, JP) ; GOTO; Kyosei;
(Kumamoto-shi, Kumamoto, JP) ; TAKEMOTO; Mitsunobu;
(Ibaraki-shi, Osaka, JP) ; KITAHARA; Tatsuya;
(Ibaraki-shi, Osaka, JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
NITTO DENKO CORPORATION
NATIONAL UNIVERSITY CORPORATION KUMAMOTO UNIVERSITY |
Ibaraki-shi, Osaka
Kumamoto-shi,Kumamoto |
|
JP
JP |
|
|
Family ID: |
1000006128325 |
Appl. No.: |
17/429247 |
Filed: |
February 3, 2020 |
PCT Filed: |
February 3, 2020 |
PCT NO: |
PCT/JP2020/003976 |
371 Date: |
August 6, 2021 |
Current U.S.
Class: |
204/291 |
Current CPC
Class: |
G01N 27/30 20130101;
G01N 27/48 20130101 |
International
Class: |
G01N 27/30 20060101
G01N027/30; G01N 27/48 20060101 G01N027/48 |
Foreign Application Data
Date |
Code |
Application Number |
Feb 13, 2019 |
JP |
2019-023535 |
Claims
1. An electrode device comprising: a first electrode; a second
electrode separated from the second electrode with a space
therebetween and; and an ion-conducting medium extending over the
first electrode and the second electrode so as to be in contact
with the first electrode and the second electrode, wherein the
ion-conducting medium is made of a bicontinuous microemulsion
containing a water phase being a continuous phase and an oil phase
being a continuous phase, and at least one of the water phase and
the oil phase is a gel.
2. The electrode device according to claim 1, wherein the first
electrode is a working electrode, and the second electrode is a
counter electrode.
3. The electrode device according to claim 2, further comprising: a
reference electrode separated from the working electrode and the
counter electrode with a space between the reference electrode and
the working electrode and a space between the reference electrode
and the counter electrode, wherein the ion-conducting medium
extending over the working electrode, the counter electrode, and
the reference electrode so as to be in contact with the working
electrode, the counter electrode, and the reference electrode.
4. The electrode device according to claim 1, wherein one of the
water phase and the oil phase is a gel.
5. The electrode device according to claim 4, wherein the oil phase
does not contain an electrolyte, and the water phase contains an
electrolyte.
6. The electrode device according to claim 1, wherein the first
electrode and the second electrode each have a flat-belt shape, and
the ion-conducting medium has a sheet shape.
Description
TECHNICAL FIELD
[0001] There are known electrochemical analyses such as cyclic
voltammetry in which an electrode device including a working
electrode, a counter electrode, and a reference electrode is
immersed in an aqueous solution containing an analyte and the
electrode potential of the working electrode is cyclically
changed.
BACKGROUND ART
[0002] In such an electrochemical analysis, first, an electrolysis
cell (electrolysis vessel) is prepared. Subsequently, an aqueous
solution is poured into the electrolysis cell, and then an
electrode device is immersed in the solution inside the vessel. In
cyclic voltammetry, for example, the diffusion constant of the
analyte is measured.
[0003] Further, as a reaction field for the electrochemical
analysis, a bicontinuous-phase microemulsions has been proposed.
(for example, see Non-patent document 1 below). In the
bicontinuous-phase microemulsion, water and oil coexist in a
bicontinuous way on the microscale. Thus, a hydrophilic substance
is dissolved in the water and a lipophilic substance dissolved in
the oil and both of the hydrophilic substance and the lipophilic
substance can electrochemically be analyzed.
CITATION LIST
Non-patent Document
[0004] Non-patent Document 1: KURAYA, Eisuke. `Development of
Technique to Evaluate Antioxidative Substance Using Bicontinuous
Microemulsion`. Kumamoto University, Sep. 25, 2015.
SUMMARY OF THE INVENTION
Problem to be Solved by the Invention
[0005] However, to electrochemically analyze the bicontinuous-phase
microemulsion in Non-patent document 1, it is necessary to contain
the bicontinuous-phase microemulsion that is a liquid in the
vessel. Thus, there are limitations to the downsizing of the
analysis device and the vessel containing the liquid is
inconvenience to handle.
[0006] The present invention provides an electrode device that can
be downsized and easy to handle.
Means for Solving the Problem
[0007] The present invention [1] includes an electrode device,
comprising: a first electrode; a second electrode separated from
the second electrode with a space therebetween and; and an
ion-conducting medium extending over the first electrode and the
second electrode so as to be in contact with the first electrode
and the second electrode, wherein the ion-conducting medium is made
of a bicontinuous microemulsion containing a water phase being a
continuous phase and an oil phase being a continuous phase, and at
least one of the water phase and the oil phase is a gel.
[0008] In the electrode device, the ion-conducting medium extends
from the first electrode to the second electrode. Thus, the ionic
conduction between the first electrode and the second electrode can
be carried out.
[0009] In addition, in the electrode device, at least one of the
water phase and the oil phase is a gel. Thus, the gel phase
includes the liquid phase or both of the phases are gels, thereby
suppressing the flux of the ion-conducting medium. Accordingly, the
ion-conducting medium can be fixed to the first electrode and the
second electrode. As a result, it is not necessary to contain the
liquid. Thus, the device can be downsized and easy to handle.
[0010] The present invention [2] includes the electrode device
described in [1] above, wherein the first electrode is a working
electrode, and the second electrode is a counter electrode.
[0011] In the structure, the electron transfer from the working
electrode allows the oxidation-reduction reaction while the ionic
conduction from the working electrode to the counter electrode in
the ion-conducting medium is ensured. By that, an electrochemical
analysis without an electrolyte solution outside the electrode
device can be carried out.
[0012] The present invention [3] includes the electrode device
described in [2] above, further comprising: a reference electrode
separated from the working electrode and the counter electrode with
a space between the reference electrode and the working electrode
and a space between the reference electrode and the counter
electrode, wherein the ion-conducting medium extending over the
working electrode, the counter electrode, and the reference
electrode so as to be in contact with the working electrode, the
counter electrode, and the reference electrode.
[0013] Using the structure, with reference to the potential of the
reference electrode, an electrochemical measurement such as
potentiometry, an electrical conductivity measurement,
amperometry-voltammetry, or an alternating-current impedance
measurement can be carried out.
[0014] The present invention [4] includes the electrode device
described in any one of the above-described [1] to [3], wherein one
of the water phase and the oil phase is a gel.
[0015] When only the water phase is a gel, the degree of freedom of
the diffusion of the fat-soluble (hydrophobic or lipophilic)
substance in the oil phase is higher than that of the case in which
both of the water phase and the oil phase are gels. Thus, the
fat-soluble analyte is dissolved and diffused in the oil phase and
can electrochemically be detected at the working electrode.
Meanwhile, the network of the gel in the water phase does not
impede the ionic conduction, and thus the fat-soluble analyte has
excellent responsiveness to the detection. Thus, the fat-soluble
analyte can accurately be analyzed.
[0016] When only the oil phase is a gel, the degree of freedom in
the water phase is higher than that in the case in which both of
the water phase and the oil phase are gels. Thus, when the
hydrophilic analyte is dissolved in the water phase, the ionic
conduction in the hydrophilic analyte is rapidly carried out and
thus the hydrophilic analyte has excellent responsiveness.
Therefore, the hydrophilic analyte can accurately be analyzed.
[0017] Therefore, using the structure, the fat-soluble analyte or
the hydrophilic analyte can accurately be analyzed.
[0018] The present invention [5] includes the electrode device
described in [4] above, wherein the oil phase does not contain an
electrolyte, and the water phase contains an electrolyte.
[0019] With the structure, when the fat-soluble analyte is
dissolved in the oil phase, the ionic conduction in the fat-soluble
analyte is carried out in the interface of the oil phase and the
water phase without containing the electrolyte in the oil phase.
Thus, the fat-soluble analyte can be analyzed without containing
the electrolyte in the oil phase.
[0020] The present invention [6] includes the electrode device
described in any one of the above-described [1] to [5], wherein the
first electrode and the second electrode each have a flat-belt
shape, and the ion-conducting medium has a sheet shape.
[0021] The structure allows the electrode device to be thinned
Effects of the Invention
[0022] The electrode device of the present invention is small and
can easily be handled.
BRIEF DESCRIPTION OF THE DRAWINGS
[0023] FIG. 1A to FIG. 1C are plan views illustrating the steps of
producing the electrode devices of the first embodiment and the
second embodiment of the present invention. FIG. 1A depicts the
step of preparing the electrode device. FIG. 1B depicts the step of
disposing a mask layer. FIG. 1C depicts the step of disposing an
ion-conducting medium.
[0024] FIG. 2A to FIG. 2D are cross-sectional views illustrating
the step of producing the electrode device of the first embodiment
and the second embodiment of the present invention. The
cross-sectional views on the left side are taken along lines X-X of
FIG. 1A to FIG. 1C. The cross-sectional views on the right side are
taken along lines Y-Y of FIG. 1A to FIG. 1C. FIG. 2A illustrates
the step of preparing the electrode device. FIG. 2B illustrates the
step of disposing the mask layer. FIG. 2C illustrates the step of
disposing a bicontinuous microemulsion that is yet to be
gelatinized. FIG. 2D illustrates the step of forming an
ion-conducting medium.
[0025] FIG. 3 is a view of a mode in which a solution containing an
analyte is electrochemically analyzed with the electrode device
illustrated in FIG. 1C to FIG. 2D.
[0026] FIG. 4 is a plan view of a variation of the electrode device
of the first embodiment illustrated in FIG. 1C (in which another
reference electrode is brought into contact with the ion-conducting
medium).
[0027] FIG. 5 is a plan view of a variation of the electrode device
of the first embodiment illustrated in FIG. 1C (that is an
electrode device without a reference electrode).
[0028] FIG. 6 is a cross-sectional view of the measurement device
used in the cyclic voltammetry of Comparative Example 1.
[0029] FIG. 7 illustrates the cyclic voltammogram and diffusion
constant of Example 1.
[0030] FIG. 8 illustrates the cyclic voltammogram and diffusion
constant of Comparative Example 1.
[0031] FIG. 9 illustrates the cyclic voltammogram of Example 2.
DESCRIPTION OF THE EMBODIMENTS
[0032] The electrode device of the present invention includes a
first electrode, a second electrode, and an ion-conducting medium
extending over the first electrode and the second electrode. The
ion-conducting medium consists of a bicontinuous microemulsion
including a water phase that is a continuous phase and an oil phase
that is a continuous phase. At least one of the water phase and the
oil phase is a gel.
First Embodiment
[0033] The first embodiment of an electrode device in which the
water phase is a gel will be described.
[0034] As illustrated in FIG. 1C and FIG. 2D, an electrode device 1
is an example of an electrode for an electrochemical analysis or an
electrochemical measurement electrode. The electrode device 1 has
an approximately plate shape having a one-side surface and the
other-side surface that face each other in a thickness direction.
Further, the electrode device 1 has an approximately rectangular
shape (longitudinally long rectangular shape) extending long in a
long-length direction orthogonal to the thickness direction and
extending short in a short-length direction orthogonal to the
thickness direction and the long-length direction in a plan
view.
[0035] The electrode device 1 includes a substrate 2, a plurality
of electrodes 3, 4, and 5, wires 9 each corresponding to the
plurality of electrodes 3, 4, and 5, a mask layer 6, and an
ion-conducting medium 7.
[0036] The substrate 2 has a one-side surface 8 and the other-side
surface that face each other in the thickness direction. Meanwhile,
the substrate 2 forms an outer shape of the electrode device 1 in
the plan view. Examples of the material of the substrate 2 include
an insulating materials such as polymers and ceramics (for example,
alumina). The dimensions of the substrate 2 are appropriately set
depending on the purpose and use of the electrode device 1. The
substrate 2 has a thickness of, for example, 3000 .mu.m or less
and, for example, 10 .mu.m or more. Further, the substrate 2 has a
length in the short-length direction of, for example, 5 mm or more
and, for example, 100 mm or less, preferably 30 mm or less. The
substrate 2 has a length in the long-length direction of, for
example, 10 mm or more, preferably, 20 mm or more and, for example,
1000 mm or less, preferably 50 mm or less.
[0037] The plurality of electrodes 3, 4, and 5 is disposed on the
one-side surface 8 of the substrate 2. Specifically, the plurality
of electrodes 3, 4, and 5 is in contact with the one-side surface 8
of the substrate 2. Further, the plurality of electrodes 3, 4, and
5 is disposed on a one-side end of the substrate 2 in the
long-length direction. The plurality of electrodes 3, 4, and 5 each
have a flat-belt shape (a strip shape).
[0038] Furthermore, the plurality of electrodes 3, 4, and 5 are
disposed with spaces therebetween. The plurality of electrodes 3,
4, and 5 includes a working electrode 3 as an example of a first
electrode, a counter electrode 4 as an example of a second
electrode, and a reference electrode 5. Preferably, the plurality
of electrodes 3, 4, and 5 consists of the working electrode 3, the
counter electrode 4, and the reference electrode 5,
respectively.
[0039] The working electrode 3 has, for example, an approximately
circular plate (disk) shape in the plan view. The working electrode
3 has a surface area of, for example, 5 mm.sup.2 or more,
preferably, 10 mm.sup.2 or more.
[0040] The counter electrode 4 is disposed relative to the working
electrode 3 with a space therebetween. Specifically, the working
electrode 4 has an approximately arc shape and shares the same
center with the working electrode 3 in the plan view. The central
angle of the working electrode 4 is, for example, more than
150.degree., preferably, more than 180.degree. and, for example,
less than 360.degree., preferably less than 270.degree.. The space
between the counter electrode 4 and the working electrode 3 (the
closest distance and the same will apply hereinafter) is, for
example, 0.1 mm or more and, for example 10 mm or less.
[0041] The reference electrode 5 is disposed relative to the
working electrode 3 and the counter electrode 4 with spaces
therebetween. Specifically, the reference electrode 5 has an
approximately arc shape (or approximately C shape, or approximately
U shape) and shares the same center with the working electrode 3 in
the plan view. Further, the reference electrode 5 has an arc shape
that is an extension of the arc shape of the counter electrode 4 in
its circumferential direction. However, the reference electrode 5
is separated from a one-side end in the circumferential direction
of the counter electrode 4 with a space therebetween in the
circumferential direction. The central angle of the working
electrode 4 is, for example, more than 0.degree., preferably, more
than 30.degree. and, for example, less than 180.degree., preferably
less than 75.degree..
[0042] The other-side ends in the long-length direction of the
plurality of electrodes 3, 4, and 5 respectively connect to
one-side ends in the long-length direction of the three wires 9.
The three wires 9 extend in the long-length direction and face each
other with spaces therebetween in the short-length direction. The
three wires 9 extend from an intermediate part in the long-length
direction of the substrate 2 to the other-side end in the
long-length direction of the substrate 2.
[0043] Examples of the materials of the plurality of electrodes 3,
4, and 5 and the wire 9 include metals, and carbon compounds.
Preferably, metals are used. Particularly, as the material of the
working electrode 3 and the counter electrode 4, more preferably,
gold is used. As the material of the reference electrode 5, more
preferably, silver is used.
[0044] The thickness of the plurality of electrodes 3, 4, and 5 and
the thickness of the wires 9 are, for example, identical and,
specifically, for example, 500 .mu.m or less, preferably 250 .mu.m
or less, more preferably 100 .mu.m or less and, for example 10
.mu.m or more.
[0045] The mask layer 6 is disposed on the one-side surface 8 of
the substrate 2 so as to cover the one-side ends of the three wires
9. The mask layer 6 has, in the plan view, an approximately
rectangular shape (film shape) extending entirely in the
short-length direction of the substrate 2 at the intermediate part
of the substrate 2 in the long-length direction. The mask layer 6
defines the plurality of electrodes 3, 4, and 5. Examples of the
material of the mask layer 6 include the above-described insulating
materials (such as polymers).
[0046] The ion-conducting medium 7 has a layer (film) shape
extending over the working electrode 3, the counter electrode 4 and
the reference electrode 5 so as to cover them. Further, the
ion-conducting medium 7 has an approximately rectangular sheet
shape including the working electrode 3, the counter electrode 4,
and the reference electrode 5 in the plan view. The ion-conducting
medium 7 is disposed on the one-side end of the one-side surface 8
of the substrate 2 in the long-length direction. The ion-conducting
medium 7 is in contact with: a one-side surface in the
thickness-direction and a side surface of the working electrode 3;
a one-side surface in the thickness direction and a side surface of
the counter electrode 4; a one-side surface in the thickness
direction and a side surface of the reference electrode 5; and the
one-side surface 8 exposed from the working electrode 3, the
counter electrode 4, and the reference electrode 5 on the substrate
10.
[0047] The ion-conducting medium 7 consists of a bicontinuous
microemulsion. The bicontinuous microemulsion includes a water
phase that is a continuous phase and, an oil phase that is a
continuous phase. In the bicontinuous microemulsion, the water
phase contains, for example, water and an electrolyte (for example,
an inorganic salt such as sodium nitrate, sodium chloride, sodium
hypochlorite, sodium hypophosphite, or sodium phosphite). The oil
phase contains, for example, an organic solvent (aromatic
hydrocarbon such as toluene, or aliphatic hydrocarbon such as
hexane). Further, the bicontinuous microemulsion contains a
surfactant (an anionic surfactant such as sodium lauryl sulfate)
and an auxiliary surfactant (lower alcohol having 1 or more and 5
or less carbons such as 2-butanol) that are located in the
interface of the water phase and the oil phase. The surfactant and
the auxiliary surfactant are located in the interface of the water
phase and the oil phase.
[0048] Examples, types, and contents (including the content of
water) of the above-described electrolyte, organic solvent,
surfactant, and auxiliary surfactant and the method of preparing
the bicontinuous microemulsion are described in detail in, for
example, Japanese Translation of PCT International Application
Publication No. H9-509196 and the above-described Non-patent
document 1.
[0049] Further, in the first embodiment, the water phase is a gel.
The water phase is prepared as a hydrogel.
[0050] As long as having a network structure formed of the water
phase, the hydrogel can be either a soft gel (including a swollen
gel) or a hard gel (for example, a silica gel including partially
dehydrated silica). As the hydrogel, preferably, a soft hydrogel in
which water is swollen is used.
[0051] In the hydrogel, a first gelatinizing agent described below
forms a three dimensional network structure at the molecular level
in the water phase.
[0052] To prepare the water phase as a soft hydrogel, the first
gelatinizing agent is contained in the water phase.
[0053] Examples of the first gelatinizing agent include first to
third types. For the first type, a gelatinizing agent material is
blended in a water phase and then allowed to react, thereby
generating the first gelatinizing agent and simultaneously
gelatinizing the water phase. For the second type, the gelatinizing
agent is blended in a water phase, and the mixture is heated to
temporarily dissolve the first gelatinizing agent in the water
phase and then cooled, thereby gelatinizing the water phase. For
the third type, the first gelatinizing agent is blended in a water
phase and mixed (without heating and cooling), thereby gelatinizing
the water phase. The above-described first to third types are not
clearly distinguished and, for example, are allowed to overlap.
[0054] Examples of the first type include synthetic polymers such
as polyacrylamide compounds, polyacrylic acid compounds, polyvinyl
alcohol, and polyamino acid compounds.
[0055] Examples of the second type include natural polymers such as
agar, gelatin, agarose, carrageenan, and alginate.
[0056] Examples of the third type include the synthetic polymers
exemplified as the first type.
[0057] These can be used singly or in combination.
[0058] Preferably, the first type and the third type are used. More
preferably, the first type, specifically, the polyacrylamide
compound is used.
[0059] The polyacrylamide compound is polymers of a monomer
component containing acrylamide monomers as the main component. The
monomer component is included in the gelatinizing agent material.
Examples of the acrylamide monomers include nonionic monomers such
as acrylamide, and methacrylamide, and anionic monomers such as
(meth)acrylamide-methylpropanesulfonate (specifically, sodium
salts). Preferably, the non-ionic monomer, more preferably,
acrylamide is used. The content of the main component (preferably,
the acrylamide monomers) in the monomer component is, for example,
more than 50 mass %, preferably 70 mass % or more.
[0060] Further, the monomer component can contain, for example, a
cross-linkable monomer having two vinyl groups such as methylenebis
(meth)acrylamide. The content of the water-soluble cross-linking
agent in the monomer component is the rest of the above-described
main component.
[0061] When the polyacrylamide compound is used as the first type,
for example, the above-described monomer component is blended
together with the water-soluble initiator in the water phase and
the oil phase is blended in the mixture to prepare a bicontinuous
microemulsion, and then the monomer component is polymerized with,
for example, light or heat, thereby preparing the first type. The
water-soluble initiator constitutes the gelatinizing agent material
together with the monomer component.
[0062] Examples of the water-soluble initiator include a thermal
initiator, and a photo initiator (specifically, a hydroxyketone
compound such as
1-[4-(2-hydroxyethoxy)-phenyl]-2-hydroxy-methyl-1-propane-1-on
(Irgacure 2959)). Preferably, a photo initiator is used. The parts
by mass of the water-soluble initiator relative to 100 parts by
mass of the monomer component is, for example, 1 part by mass or
more, preferably 5 parts by mass or more and, for example, 25 parts
by mass or less, preferably 15 parts by mass or less.
[0063] The ratio of the first gelatinizing agent (or the ratio of
the gelatinizing agent material) (the ratio of the monomer
component and the water-soluble initiator in total) relative to 100
parts by mass of the water and the electrolyte in total is, for
example, 1 part by mass or more, preferably 5 parts by mass or more
and, for example, 40 parts by mass or less, preferably 25 parts by
mass or less.
[0064] The ion-conducting medium 7 is a bicontinuous microemulsion
where the water phase gelatinized with the first gelatinizing agent
and the oil phase having a higher degree of freedom than that of
the water phase are each formed as a continuous phase. The
electrolyte is contained in the water phase. The surfactant and the
auxiliary surfactant are located in the interface of the water
phase and the oil phase.
[0065] In the bicontinuous microemulsion, the water phase and the
oil phase are continuous. Thus, the gel of the water phase can form
a three dimensional network structure. The oil phase exists in pore
spaces of the three dimensional network structure. The oil phase is
included (incorporated) as a liquid in the gelatinized water phase
and can move among the pore spaces relatively freely.
[0066] The degree of freedom of the oil phase has a higher than the
degree of freedom of the gelatinized water phase. Meanwhile, in the
bicontinuous microemulsion, the oil phase exists in the
above-described tiny pore spaces, and thus the fall or leakage of
the oil phase from the water phase in the ion-conducting medium 7
is suppressed.
[0067] The thickness of the ion-conducting medium 7 is a distance
between the one-side surface 8 of the substrate 10 and the one-side
surface of the ion-conducting medium 7 in the thickness direction
and is, for example, 10 .mu.m or more, preferably 100 .mu.m or more
and, for example, 1500 .mu.m or less.
[0068] To produce the electrode device 1, for example, as
illustrated in FIG. 1A and FIG. 2A, the electrode substrate 10
including the substrate 2 and the plurality of electrodes 3, 4, and
5 disposed on the one-side surface 8 is first prepared. The
electrode substrate 10 includes the three wires 9 continuous to the
plurality of electrodes 3, 4, and 5 on the one-side surface 8 of
the substrate 2. As the electrode substrate 10, a commercially
available product can be used.
[0069] Subsequently, as illustrated in FIG. 1B and FIG. 2B, the
mask layer 6 is disposed on the electrode substrate 10. For
example, a film made of polymers is adhered to the electrode
substrate 10.
[0070] Thereafter, as illustrated in FIG. 1C, and FIG. 2C to FIG.
2D, the ion-conducting medium 7 is disposed on the electrode
substrate 10 so that the ion-conducting medium 7 is in contact with
and extends over the working electrode 3, the counter electrode 4,
and the reference electrode 5.
[0071] For example, first, a bicontinuous microemulsion in which
the water phase is yet to be gelatinized is prepared. Specifically,
when the first gelatinizing agent is the first type, water, an
electrolyte, an organic solvent, a gelatinizing agent material (a
monomer component and a water-soluble initiator), a surfactant, and
an auxiliary surfactant are blended and mixed. The electrolyte can
be prepared with an electrolyte aqueous solution previously
dissolved in water, and then be blended.
[0072] In this manner, the bicontinuous microemulsion containing
the water phase containing the water, the electrolyte, and the
gelatinizing agent material; the oil phase containing the organic
solvent; and the surfactant and auxiliary surfactant existing in
the interface between the water phase and the oil phase.
[0073] Subsequently, the above-described bicontinuous microemulsion
13 is disposed on the electrode substrate 10 so as to be in contact
with and extend over the working electrode 3, the counter electrode
4, and the reference electrode 5. Specifically, the bicontinuous
microemulsion 13 is, for example, applied (including dropped) on
the working electrode 3, counter electrode 4, and reference
electrode 5 of the electrode substrate 10 (see the right side view
of FIG. 2B).
[0074] At the time, the mask layer 6 functions as a weir portion
that suppresses the flow of the bicontinuous microemulsion 13 that
a liquid at room temperature (25.degree. C.) toward the wires
9.
[0075] Thereafter, the water phase in the bicontinuous
microemulsion 13 is gelatinized. When the initiator contains a
photo initiator, the bicontinuous microemulsion 13 is irradiated
with ultraviolet light. Specifically, for example, a covering
member 11 (phantom line) having translucency is disposed on one
side of the bicontinuous microemulsion in the thickness direction.
Subsequently, through the covering member 11, the bicontinuous
microemulsion 13 is irradiated with ultraviolet light. In this
manner, in the water phase, the monomer component in the
gelatinizing agent material is polymerized in the presence of the
water-soluble initiator, thereby preparing the first gelatinizing
agent. At the same time as the preparation of the first
gelatinizing agent, a first gel forms the three dimensional network
structure at the molecular level in the water phase to form a
network structure in the water phase. In this manner, the
ion-conducting medium 7 in which the water phase becomes a gel
(chemical gel) is prepared.
[0076] In the ion-conducting medium 7, the electrolyte is contained
in the water phase and exists as an ion in the water phase. In the
ion-conducting medium 7, the surfactant and the auxiliary
surfactant exist in the interface of the water phase and the oil
phase.
[0077] In this manner, the electrode device 1 including the
electrode substrate 10, and the ion-conducting medium 7 in contact
with and extending over the working electrode 3, the counter
electrode 4, and the reference electrode 5 is produced.
[0078] Next, a method of carrying out cyclic voltammetry of a
solution 14 containing a fat-soluble (hydrophobic or lipophilic)
analyte with the electrode device 1 will be described as an example
of a potential control measurement.
[0079] The electrode device 1 is prepared in the method described
above. Meanwhile, the other-side ends of three electrodes 9 in the
long-length direction are electrically connected to a potentiostat
through lines not illustrated.
[0080] Subsequently, as illustrated in FIG. 3, the solution 14 is
disposed on the ion-conducting medium 7.
[0081] The solution 14 includes, for example, a fat-soluble
analyte, and, a fat-soluble solvent dissolving the fat-soluble
analyte. The fat-soluble analyte is not especially limited and
includes, for example, ferrocene, or an antioxidative substance.
Examples of the fat-soluble solvent includes the above-described
organic solvents (aromatic solvents such as toluene), edible oils
(such as olive oil), and oils for cosmetics.
[0082] For example, the ion-conducting medium 7 is impregnated with
the solution by applying (or dropping). Specifically, the solution
is applied (dropped) to the one-side surface of the ion-conducting
medium 7 in the thickness direction from one side (for example, an
upper side) of the ion-conducting medium 7 in the thickness
direction. The amount of application (drop) of the solution is not
especially limited as long as the ion-conducting medium 7 is
impregnated and the ionic conduction between the working electrode
3 and the counter electrode 4 is ensured.
[0083] In this manner, the analyte is fat-soluble and thus
distributed to the oil phase. In other words, the fat-soluble
analyte moves not to the water phase that is a gel but to the oil
phase.
[0084] Thereafter, by the cyclic voltammetry, the electrode
potential of the working electrode 3 is cyclically changed.
[0085] Then, the ions of the analyte are transferred from the
interface continuously existing in proximity to the oil phase (the
interface of the oil phase and the water phase) through the water
phase between the working electrode 3 and the counter electrode
4.
[0086] In this manner, for example, the peak current is detected.
Based on the peak current, a diffusion constant D of the
fat-soluble analyte is obtained. Specifically, by assigning each
parameter to the following expression (1), the diffusion constant D
is obtained.
[ Expression .times. .times. 1 ] .times. ##EQU00001## i p = 0.4463
.times. nFAC .function. ( nFvD RT ) 1 2 ( 1 ) ##EQU00001.2##
[0087] Each of the parameters in n the expression is described
below.
[0088] i.sub.p: the peak current
[0089] n=equivalent/mol of the analyte
[0090] A=the surface area cm.sup.2 of the working electrode 3
[0091] D=the diffusion coefficient (cm.sup.2/sec)
[0092] C=the concentration of the analyte (mol/cm.sup.3)
[0093] v=the sweep velocity (V/sec)
[0094] Meanwhile, in the electrode device 1, the ion-conducting
medium 7 extends from the working electrode 3 to the counter
electrode 4. Thus, the ionic conduction between the working
electrode 3 and the counter electrode 4 can be carried out.
[0095] In addition, in the electrode device 1, the water phase in
the bicontinuous microemulsion is a gel. Then, the gel of the water
phase includes the liquid of the oil phase, and thus the flux of
the ion-conducting medium 7 is suppressed. Accordingly, the
ion-conducting medium 7 is fixed to the working electrode 3 and the
counter electrode 4. As a result, it is not necessary to contain
the solution 14 as described in Non-patent document 1 (see FIG. 6).
Hence, the device can be downsized and the electrode device 1 can
easily be handled.
[0096] Further, in the electrode device 1, while the electron
transfer from the working electrode 3 allows an oxidation-reduction
reaction, the ionic conduction from the working electrode 3 to the
counter electrode 4 in the ion-conducting medium 7 is ensured.
Thus, an electrochemical analysis, specifically, cyclic voltammetry
can be carried out without having an electrolyte solution outside
the electrode device 1.
[0097] Furthermore, in the electrode device 1, with reference to
the potential of the reference electrode 5, an electrochemical
measurement such as potentiometry, an electrical conductivity
measurement, amperometry-voltammetry, or an alternating-current
impedance measurement can be carried out.
[0098] Furthermore, in the electrode device 1, the fat-soluble
analyte is dissolved in the oil phase. Thus, without containing the
electrolyte in the oil phase, the ionic conduction in the
fat-soluble analyte can rapidly be carried out in the interface of
the oil phase and the water phase. Thus, the fat-soluble analyte
can be analyzed without the electrolyte in the oil phase.
[0099] Furthermore, in the electrode device 1, while the working
electrode 3, the counter electrode 4 and the reference electrode 5
each have a flat-belt shape, the ion-conducting medium 7 has a
sheet shape. Thus, the electrode device 1 can be thinned.
Variations of the First Embodiment
[0100] In each of the following variations, the same members and
steps as in the first embodiment will be given the same numerical
references and the detailed description thereof will be omitted.
Further, each of the variations has the same operations and effects
as those of the first embodiment unless especially described
otherwise. Furthermore, the first embodiment and the variations can
appropriately be combined.
[0101] In the method of producing the electrode device 1 in the
first embodiment, first, the bicontinuous microemulsion in which
the water phase is yet to become a gel is disposed on the working
electrode 3, the counter electrode 4, and the reference electrode 5
and, thereafter, the water phase is gelatinized.
[0102] However, although not illustrated, for example, after a film
of a bicontinuous microemulsion with a gelatinized water phase is
prepared, the film of the bicontinuous microemulsion can be brought
into contact with (adhered to) the working electrode 3, the counter
electrode 4, and the reference electrode 5. At the time, by
previously impregnating the film of the bicontinuous microemulsion
with a solution containing the analyte and, thereafter, bringing
the film impregnated with the solution into contact with the
working electrode 3, the counter electrode 4, and the reference
electrode 5, the application (drop) of the solution 14 can be
omitted.
[0103] Further, as an preferable example of the gelatinizing agent,
the first type is used to describe the preparation of the
ion-conducting medium 7. However, as the third type that is another
preferable example of the gelatinizing agent, synthetic polymers (a
polyamide compound) that are previously (separately) synthesized
can be blended (dispersed) in the water phase to gelatinize the
water phase.
[0104] Furthermore, in FIG. 3, the solution containing the analyte
is applied (dropped) on the one-side surface of the ion-conducting
medium 7 in the thickness direction. However, the solution
containing the analyte can alternatively be applied on the
other-side surface of the ion-conducting medium 7 separately
produced in the thickness direction and, thereafter, the other-side
surface of the ion-conducting medium 7 is brought into contact with
the working electrode 3, the counter electrode 4, and the reference
electrode 5. Alternatively, it is also possible to release the
ion-conducting medium 7 formed on the electrode substrate 10 from
the electrode substrate 10 so that a gap is formed therebetween
and, thereafter, dispose the solution 14 containing the analyte the
gap between the ion-conducting medium 7 and the electrode substrate
10 and, thereafter, dispose the ion-conducting medium 7 on the
electrode substrate 10 again.
[0105] Further, although not illustrated, the shape of each of the
working electrode 3, the counter electrode 4, and the reference
electrode 5 is not limited to the above, and can be, for example, a
comb shape (a comb-shaped electrode).
[0106] Preferably, the working electrode 3, the counter electrode
4, and the reference electrode 5 are each formed into a flat-belt
shape, and the ion-conducting medium 7 is formed into a sheet
shape. Using the structure, the electrode device 1 can be
thinned
[0107] Furthermore, in the first embodiment, the electrode device 1
includes the substrate 2. However, for example, although not
illustrated, the electrode device 1 does not need including the
substrate 2.
[0108] Furthermore, in the first embodiment, the electrode device 1
includes the mask layer 6. However, for example, although not
illustrated, the electrode device 1 does not need including the
mask layer 6.
[0109] In the structures, the ion-conducting medium 7 extends over
the working electrode 3, the counter electrode 4, and the reference
electrode 5 while being in contact therewith. Thus, while the
oxidation-reduction reaction is allowed in the working electrode 3,
the corresponding oxidation-reduction reaction is allowed in the
counter electrode 4. By that means, potentiometry can accurately be
carried out with respect to the potential of the reference
electrode 5.
[0110] Further, in addition to the potential control measurement, a
galvanostatic measurement (current control measurement) can be
carried out. In the structure, the ion-conducting medium 7 extends
over the working electrode 3, the counter electrode 4, and the
reference electrode 5 while being in contact therewith. Thus, the
galvanostatic measurement can accurately be carried out.
[0111] Furthermore, as illustrated in FIG. 5, the electrode device
1 can include the working electrode 3 and the counter electrode 4
without including the reference electrode 5. In the structure,
using the working electrode 3 and the counter electrode 4, the
potential difference of the analytes caused therebetween can be
measured. Specifically, while the electron transfer from the
working electrode 3 allows an oxidation-reduction reaction, the
ionic conduction from the working electrode 3 to the counter
electrode 4 in the ion-conducting medium 7 is ensured. Thus, cyclic
voltammetry can be carried out without the electrolyte solution
outside the electrode device 1.
[0112] With the electrode device 1 including the above-described
working electrode 3 and the counter electrode 4 without including
the reference electrode 5 as the device structure, potentiometry
and a galvanostatic measurement can be carried out. In this method,
for example, the reference electrode 5 is prepared as a separate
member of the electrode device 1 (the reference electrode 5
included in a separate external device), and the electrode device 1
including the working electrode 3 and the counter electrode 4 is
prepared. Thereafter, in a cyclic voltammetry measurement, as the
thick solid line of FIG. 4 shows, the separate reference electrode
5 is brought into contact with (pressed to) the ion-conducting
medium 7 from the outside (for example, the one side in the
thickness direction).
Second Embodiment
[0113] In the following second embodiment, the same members and
steps as in the first embodiment and the variations will be given
the same numerical references and the detailed description thereof
will be omitted. Further, the second embodiment has the same
operations and effects as those of the first embodiment and the
variations unless especially described otherwise. Furthermore, the
first embodiment, the variations, and the second embodiment can
appropriately be combined.
[0114] The second embodiment in which electrode device with a oil
phase that is a gel will be described.
[0115] The oil phase is prepared as an organogel.
[0116] The organogel can be either a soft gel (including a swollen
gel) or a hard gel as long as having a network structure formed of
the oil phase. As the organogel, preferably, a soft gel is
used.
[0117] In the organogel, a second gelatinizing agent described
below forms a three dimensional network structure at the molecular
level in the oil phase.
[0118] To prepare the oil phase as a soft organogel, the second
gelatinizing agent is blended in the oil phase.
[0119] Examples of the second gelatinizing agent include a fourth
type and a fifth type. For the fourth type, the second gelatinizing
agent is blended into the oil phase, the mixture is heated to
temporarily dissolve the second gelatinizing agent into the oil
phase and, thereafter, the mixture is cooled, thereby gelatinizing
the oil phase. For the fifth type, the second gelatinizing agent is
blended and mixed into the oil phase (without heating and cooling),
thereby gelatinizing the oil phase.
[0120] Examples of the fourth type include hydroxycarboxylic
acid.
[0121] Examples of the fifth type include oil-soluble polymers and
amino acid gelatinizing agent.
[0122] These can be used singly or in combination.
[0123] The above-described second gelatinizing agents (the fourth
and fifth types) are described in, for example, Japanese Unexamined
Patent Publication No. 2013-141664.
[0124] As the second gelatinizing agent, preferably, the fourth
type, specifically, hydroxycarboxylic acid is used. More
preferably, hydroxycarboxylic acid having 12 or more and 22 or less
carbons is used. Even more preferably, 12-hydroxystearic acid is
used.
[0125] The ratio of the second gelatinizing agent to 100 parts by
mass of the organic solvent is, for example 1 part by mass or more,
preferably 5 parts by mass or more and, for example, 40 parts by
mass or less, preferably 25 parts by mass or less.
[0126] In the second embodiment, the ion-conducting medium 7 is a
bicontinuous microemulsion in which the oil phase gelatinized by
the second gelatinizing agent and the water phase having a higher
degree of freedom than that of the oil phase are each formed as a
continuous phase. The electrolyte is included in the water
phase.
[0127] Although having a high degree of freedom, the water phase
can exist in proximity to the gelatinized oil phase in the
bicontinuous microemulsion. Thus, the fall or leakage of the water
phase from the oil phase in the ion-conducting medium 7 is
suppressed.
[0128] In a method of producing an electrode device 1, as
illustrated in FIG. 1A and FIG. 2A, an electrode substrate 10 is
prepared.
[0129] Next, as illustrated in FIG. 1B and FIG. 2B, a mask layer 6
is disposed on the electrode substrate 10.
[0130] Thereafter, as illustrated in FIG. 1C, FIG. 2C, and FIG. 2D,
an ion-conducting medium 7 is disposed on the electrode substrate
10 so that ion-conducting medium 7 is in contact with and extends
over a working electrode 3, a counter electrode 4 and a reference
electrode 5.
[0131] First, a bicontinuous microemulsion in which the oil phase
is yet to become a gel is prepared. Specifically, when the second
gelatinizing agent is the fourth type, water, an electrolyte, an
organic solvent, a second gelatinizing agent, a surfactant and an
auxiliary surfactant are blended and mixed to prepare a mixture.
Thereafter, the mixture is heated. The heating temperature is, for
example, 30.degree. C. or more, preferably 35.degree. C. or more
and, for example, 80.degree. C. or less, preferably 70.degree. C.
or less. Thereafter, the heated mixture is disposed on the working
electrode 3, the counter electrode 4, and the reference electrode 5
in the electrode substrate 10. Specifically, the mixture is applied
to the electrode substrate 10. In this manner, an application film
of the bicontinuous microemulsion is prepared.
[0132] Thereafter, the application film of the bicontinuous
microemulsion is cooled down to room temperature (25.degree.
C.).
[0133] In this manner, the second gelatinizing agent makes the oil
phase a gel (specifically, a physical gel). In this manner, on a
one-side surface 8 of the electrode substrate 10, the
ion-conducting medium 7 in which the oil phase is a gel is
formed.
[0134] As the ion-conducting medium 7, the bicontinuous
microemulsion that contains the water phase containing the water
and the electrolyte, the oil phase containing the organic solvent
and thus being a gel, and the surfactant and auxiliary surfactant
existing in the interface between the water phase and the oil phase
is prepared.
[0135] Next, using the electrode device 1, cyclic voltammetry of an
aqueous solution containing a hydrophilic (water-soluble) analyte
will be described.
[0136] The aqueous solution includes, for example, the
above-described hydrophilic analyte and water dissolving the
analyte. As long as being ionic, the hydrophilic analyte is not
especially limited and the examples thereof include potassium
ferricyanide (potassium hexacyanoferrate) and viologen.
[0137] In the cyclic voltammetry measurement, the analyte is
hydrophilic (water-soluble) and thus, distributed to the water
phase. In other words, the hydrophilic analyte moves not to the oil
phase that is a gel but to the water phase and moves between the
working electrode 3 and the counter electrode 4.
[0138] In this manner, for example, the peak current is detected
and, based on the detected peak current, a diffusion constant D of
the hydrophilic analyte is obtained.
[0139] In the electrode device 1, the oil phase is a gel. Thus, the
gel of the oil phase includes the liquid of the water phase, and
thereby suppressing the flux of the ion-conducting medium 7.
Accordingly, the ion-conducting medium 7 can be fixed to the
working electrode 3 and the counter electrode 4. As a result, it is
not necessary to contain the solution 14 as described in Non-patent
document 1 (see FIG. 6). Thus, the electrode device 1 can be
downsized and easily be handled.
Third Embodiment
[0140] In the third embodiment, the same members and steps as in
the first embodiment, the variations, and the second embodiment
will be given the same numerical references and the detailed
description thereof will be omitted. Further, the third embodiment
has the same operations and effects as those of the first
embodiment, the variations, and the second embodiment unless
especially described otherwise. Furthermore, the first embodiment,
the variations, the second embodiment, and the third embodiment can
appropriately be combined.
[0141] In an ion-conducting medium 7, both of the water phase and
the oil phase can be gels.
[0142] To prepare the ion-conducting medium 7, the water phase is
gelatinized in conformity with the producing method in the first
embodiment, and the oil phase is gelatinized in conformity with the
second embodiment.
[0143] In the structure, both of the water phase and the oil phase
are gels and thus can be fixed to the working electrode 3, the
counter electrode 4, and the reference electrode 5 more firmly than
in the first embodiment and the second embodiment.
[0144] Meanwhile, to accurately analyze a fat-soluble analyte or a
hydrophilic analyte, the first embodiment or the second embodiment
is more appropriate than the third embodiment.
[0145] In the first embodiment, only the water phase is a gel.
Thus, the degree of freedom of the diffusion of a fat-soluble
substance in the oil phase is higher than that of the third
embodiment in which both of the water phase and the oil phase are
gels. Hence, the fat-soluble analyte is dissolved and diffused into
the oil phase and thus can electrochemically be detected in the
working electrode 3. Meanwhile, the network of the gel in the water
phase does not impede the ionic conduction and thus the fat-soluble
analyte has excellent responsiveness to the detection. Thus, the
fat-soluble analyte can accurately be analyzed.
[0146] In the second embodiment, only the oil phase is a gel. Thus,
the degree of freedom of in the water phase is higher than that of
the third embodiment in which both of the water phase and the oil
phase are gels. Hence, when a hydrophilic analyte is dissolved into
the water phase, the ionic conduction in the hydrophilic analyte
can rapidly be carried out. Thus, the hydrophilic analyte has
excellent responsiveness. As a result, the hydrophilic analyte can
accurately be analyzed.
[0147] Accordingly, the first embodiment and the second embodiment
can respectively analyze a fat-soluble analyte and a hydrophilic
analyte more accurately than the third embodiment.
EXAMPLES
[0148] The present invention will be more specifically described
below with reference to Examples and Comparison Example. The
present invention is not limited to any of the Examples and
Comparison Example. The specific numeral values used in the
description below, such as mixing ratios (contents), physical
property values, and parameters can be replaced with corresponding
mixing ratios (contents), physical property values, parameters in
the above-described "DESCRIPTION OF EMBODIMENTS", including the
upper limit value (numeral values defined with "or less", and "less
than") or the lower limit value (numeral values defined with "or
more", and "more than").
Example 1
[0149] All the components shown in Table 1 were blended in
accordance with the amounts shown in Table 1, thereby preparing a
bicontinuous microemulsion.
[0150] Separately, as illustrated in FIG. 1A and FIG. 2A, an
electrode substrate 10 including a substrate 2, a working electrode
3, a counter electrode 4, and a reference electrode 5 was prepared.
Subsequently, as illustrated in FIG. 1B and FIG. 2B, a mask layer 6
made of a polymer film was adhered to the electrode substrate 10.
The material of the substrate 2 was alumina.
[0151] The surface area of the working electrode 3 was 12.56
mm.sup.2. The material of the working electrode 3 and the counter
electrode 4 was gold and the material of the reference electrode 5
was silver.
[0152] Next, the above-described bicontinuous microemulsion was
dropped on one side of the electrode substrate 10 in the thickness
direction so that the bicontinuous microemulsion would be in
contact with and extend over the working electrode 3, the counter
electrode 4, and the reference electrode 5.
[0153] Thereafter, the bicontinuous microemulsion 13 was covered
with a covering member 11 made of glass. Subsequently, the
bicontinuous microemulsion 13 was irradiated with ultraviolet
light. By that means, a first gelatinizing agent was prepared and
simultaneously the water phase was gelatinized. In this manner, the
ion-conducting medium 7 was prepared. The thickness of the
ion-conducting medium 7 was 1000 .mu.m.
[0154] Next, 0.1 cm.sup.3 of a toluene solution of ferrocene (a
fat-soluble analyte) was dropped on a one-side surface of the
ion-conducting medium 7 in the thickness direction. The ferrocene
has a concentration of 5 mM.
[0155] After 1 minute passed since the drop, cyclic voltammetry was
carried out using a potentiostat connected to the electrode device
1.
[0156] FIG. 7 depicts the cyclic voltammogram and diffusion
constant obtained in Example 1.
Comparative Example 1
[0157] Except that the water phase of the bicontinuous
microemulsion was not gelatinized and an electrolysis cell 12 was
separately prepared as illustrated in FIG. 6, the same process as
Example 1 was carried out.
[0158] Next, 10 cm.sup.3 of the same bicontinuous microemulsion 13
as Example 1 in which both of the oil phase and the water phase
were not gels but liquids was inserted into the electrolysis cell
12.
[0159] Separately, as illustrated in FIG. 1A and FIG. 2A, an
electrode substrate 10 was prepared. Subsequently, as illustrated
in FIG. 1B and FIG. 2B, a mask layer 6 is disposed on the electrode
substrate 10 thereby defining a working electrode 3, a counter
electrode 4, and a reference electrode 5.
[0160] Next, as illustrated in FIG. 6, the substrate 10, the
working electrode 3, the counter electrode 4, and the reference
electrode 5 were immersed into the bicontinuous microemulsion 13.
Thereafter, cyclic voltammetry was carried out.
[0161] FIG. 8 depicts the cyclic voltammogram and diffusion
constant obtained in Comparative Example 1.
[0162] Example 2
[0163] The same process as Example 1 was carried out except that
the preparation of the ion-conducting medium 7 was changed as
described below, the oil phase was gelatinized, and the method of
preparing the gel was changed as described below.
[0164] In other words, all the components shown in Table 2 were
blended and mixed in accordance with the amounts shown in Table 2,
thereby preparing the mixture (a bicontinuous microemulsion). Then,
the mixture was heated to 40.degree. C.
[0165] Subsequently, the heated mixture was applied to an electrode
substrate 10 disposed on a hot plate heated to 40.degree. C.,
thereby preparing an application film made of the mixture.
[0166] Thereafter, a covering member 11 with translucency was
disposed on a one-side surface in the thickness direction of the
application film.
[0167] Thereafter, the application film (the mixture) was cooled
down to 25.degree. C., thereby gelatinizing the oil phase (as a
physical gel). In this manner, an ion-conducting medium 7 in which
the oil phase was a gel was prepared.
[0168] Next, 0.1 cm.sup.3 of an aqueous solution of potassium
ferricyanide (III) (a hydrophilic analyte) was dropped on a
one-side surface in the thickness direction of the ion-conducting
medium 7. The potassium ferricyanide (III) had a concentration of 5
mM.
[0169] After 1 minute passed since the drop, cyclic voltammetry was
carried out using a potentiostat connected to the electrode device
1.
[0170] FIG. 9 depicts the cyclic voltammogram and diffusion
constant obtained in Example 2.
[0171] <Observations>
(1) Example 1
[0172] As FIG. 7 shows, in Example 1, with the ion-conducting
medium 7 of which water phase was a gel, the cyclic voltammetry of
ferrocene that was a fat-soluble analyte was carried out. Further,
the cyclic voltammograms of the Example 1 and Comparative Example 1
were almost the same and the diffusion constants thereof were
nearly identical as well. As a result, it is determined that the
excellent accuracy of the cyclic voltammetry was maintained in
Example 1.
(2) Example 2
[0173] As FIG. 9 shows, in Example 2, with the ion-conducting
medium 7 of which oil phase was a gel, the cyclic voltammetry of
potassium ferricyanide (III) that was a hydrophilic analyte was
carried out.
TABLE-US-00001 TABLE 1 Phase Type Amount Oil Organic solvent
Toluene 10 ml phase Water Electrolyte aqueous 1M Sodium 10 ml phase
solution nitrate aqueous solution Gelatinizing Acrylamide
Acrylamide 1.777 g agent monomer material Cross- N,N'-methyl-
0.3620 g (First type) linkable enebisacryl- monomer amide Photo
Irgacure 0.2028 g initiator 2959 Surfactant Sodium 9.030 g lauryl
sulfate Auxiliary surfactant 2-butanol 6.0 ml
TABLE-US-00002 TABLE 2 Phase Type Amount Oil phase Organic solvent
Toluene 20 ml Second gelatinizing agent 12-hydroxystearic 3.00 g
(Fourth type) acid Water Water 20 ml phase Sodium chloride 1.30 g
Surfactant Sodium lauryl sulfate 2.50 g Auxiliary surfactant
2-butanol 5.00 ml
[0174] While the illustrative embodiments of the present invention
are provided in the above description, such is for illustrative
purpose only and it is not to be construed as limiting in any
manner. Modification and variation of the present invention that
will be obvious to those skilled in the art is to be covered by the
following claims.
INDUSTRIAL APPLICABILITY
[0175] The cyclic voltammetry is used for, for example, cyclic
voltammetry.
DESCRIPTION OF REFERENCE NUMERALS
[0176] 1 electrode device
[0177] 3 working electrode (an example of the first electrode)
[0178] 4 counter electrode (an example of the second electrode)
[0179] 7 ion-conducting medium
[0180] 13 bicontinuous microemulsion
* * * * *